Something leaking when I pull a hose?

[Apex3]

When I pull one of the hoses from the driver side valve cover, I hear a hissing like something is leaking out, I thought it was refrigerant the first time around but now I don't know. Anyone know what it is? I'm not sure if anything is actually leaking out or not, it doesn't come out of the hose or valve cover and it doesn't stop immediately when I plug either one.

I assume this happens to everyone, but I want to make sure I don't need to replace something that's coming out.

[Legacy777]

What hose are you pulling on?

[Apex3]

On the driver side valve cover, attaches here:

[Legacy777]

That inner hose is hooked to the plastic pipe under the intake manifold that hooks into the center crank case vent on the block. i would think that the hissing is just blow by gasses coming out the hose.

[Apex3]

Okay sweet thanks!